A common problem among Audis and Volkswagens involves ignition coil packs suddenly failing and causing your engine's cylinders to misfire. Though you may still be able to drive your car if an ignition coil pack has gone bad, ignoring it will only make it worse and cause other coil packs to degrade. Fortunately, the procedure to change them is simple, takes only a few minutes and requires only a flat-blade screwdriver along with new coil packs. The procedure for changing coil packs in the Audi TT duplicates that of other VW and Audi models, as the two manufacturers share the same engine platforms.
Park your Audi TT on a level surface, and pop the car's bonnet.
Remove the plastic engine cover that surrounds the oil filler neck to reveal the coil packs. Remove any plastic screws securing the engine cover in place using your flat-blade screwdriver.
Position the head of the screwdriver underneath the top of the coil pack, pressing down on the screwdriver's handle to pry the coil pack loose. Once you have loosened the coil pack, gently pull it up and out.
Press down on the plastic notch at the base of the coil pack's connector, and pull the coil pack out of the wiring harness.
Insert the new coil pack into the wiring harness, and gently slide it back down on top of the spark plug. Press and click it into place to secure it.
Repeat steps 4 and 5 on any other coil packs you plan to replace.
Reinstall the plastic engine cover and close your bonnet to complete the procedure.